Dual function solid state converter

ABSTRACT

A dual function solid state power converter operable from a three phase AC input current simultaneously provides; an AC or DC output current on an aircraft power cable to provide ground power to a parked aircraft, and a low voltage DC current on a battery charging power cable to charge batteries in nearby service vehicles. The power converter includes an AC to DC converter which converts the current on an internal DC bus, a DC to AC converter which converts the DC bus current to an AC current at a higher voltage and frequency, or a DC to DC converter which converts the DC bus current to a lower voltage DC, for supplying ground power to a parked aircraft, and a DC to DC converter for converting the DC bus current to a lower voltage battery charging current on the battery charging cable.

CROSS-REFERENCE TO RELATED APPLICATION

None.

BACKGROUND OF THE INVENTION

I. Field of the Invention

The present disclosure relates generally to electrical power managementin airport environments, and more particularly, to a multi-functionsolid state converter which simultaneously supplies AC or DC groundpower to a parked aircraft and DC battery charging current to one ormore electrically-powered ground support vehicles, such as electricaircraft tugs or electric cargo loaders.

II. Description of the Prior Art

Ground support equipment, such as aircraft tugs or cargo loaders, hasbeen predominantly powered by internal combustion engines that burngasoline or diesel fuel. With advances in technology related toelectrically powered vehicles, electrically powered ground supportequipment has become more cost effective to operate and more prevalentat airports, particularly where emissions and noise are criticalenvironmental considerations.

While the increased use of electrically powered ground support equipmenthas reduced the demand for petroleum based fuels at airports, the needfor charging the batteries of such equipment has imposed capacityrequirements on airport electrical power distribution systems. Moreover,these power distribution systems often run over considerable distances,and additional electrical distribution centers have to be installed tosupport battery charging at multiple remote locations. This hasundesirably added to the expense of introducing more electricallypowered ground support equipment at airports.

One way to mitigate the need for additional electrical powerdistribution centers at airports is to have ground support equipmentbattery charging accomplished by equipment that is already installed andused on a low duty cycle basis, such as, for example, the powerconverters used to supply ground power to parked aircraft. These powerconverters are often installed on the aircraft boarding passengerbridges used at airports to provide a walkway between parked aircraftand a terminal gate for loading unloading passengers, and are typicallypowered into an extended position following aircraft arrival at the gateand is returned to a retracted position just prior to aircraftdeparture.

In accordance with the present disclosure, a dual-function solid-stateconverter, which may be advantageously mounted on a passenger boardingbridge, is provided to supply ground power to a parked aircraft andbattery charging power to nearby electrically powered ground supportequipment.

One problem that may arise with charging ground support equipment from apower converter mounted on an aircraft boarding bridge is that movementof the bridge may damage parked ground support vehicles under charge andthe cables supplying battery charging current to these vehicles. Infurther accord with the present disclosure, a dual function converter isprovided with an electrical interlock circuit which prevents movement ofthe passenger bridge when the battery charging function of the converteris in use.

Accordingly, it is a general object of the present disclosure to providea dual function solid state power converter which, in addition tosupplying ground power to parked aircraft, provides power forefficiently charging the batteries of aircraft ground support vehicles.

It is a more specific object of the present disclosure to provide a dualfunction solid state converter for supplying ground power to an aircraftand power for charging batteries, which is mounted on a passengerboarding bridge and includes a circuit for inhibiting motion of thebridge when the battery charging function is in use.

These and other objects, features and advantages of this disclosure willbe more clearly understood through a consideration of the followingdetailed description.

SUMMARY OF THE DISCLOSURE

According to one embodiment of the present disclosure, there is provideda dual purpose power converter, operable from an applied alternatingcurrent supply and providing a primary AC or DC output current forsupplying aircraft ground power and a secondary DC output current forbattery charging. The converter includes a rectifier circuit forconverting the applied alternating current to a direct current; aninverter circuit for converting the direct current to the primary ACoutput current; and a direct current conversion circuit for convertingthe direct current to a secondary DC output current.

There is also provided a dual purpose power converter operable from anapplied alternating current supply and providing a primary AC or DCoutput current for aircraft ground power and a secondary DC outputcurrent for battery charging, the power converter being adapted for usein a jetway adapted to service an aircraft parked on an associated ramp.The power converter includes a first cable set for connecting theprimary AC or DC output current to the aircraft and a second cable setfor connecting the secondary DC output current to a ground servicevehicle parked on the ramp, whereby the second cable set has a deployedstate enabling the cable to extend to the ramp to connect to the groundservice vehicle and a retracted state depending from the jetway and freeand clear of the ramp. The jetway includes an electrically-poweredpositioning system for positioning the jetway on the ramp relative tothe aircraft and a motion inhibit circuit for preventing movement of thejetway when the second cable set is not retracted.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will be more fully understood by reference to thefollowing detailed description of one or more preferred embodiments whenread in conjunction with the accompanying drawings, in which likereference characters refer to like parts throughout the views and inwhich:

FIG. 1 is a perspective view of a passenger boarding bridge having amultiple function solid state power converter mounted thereon, showingthe power converter connected to supply ground power to an adjacentparked aircraft.

FIG. 2 is a perspective view of the passenger bridge of FIG. 1 showingthe multiple function solid state power converter connected to anelectrically powered aircraft tug by means of an associated reel andcable assembly to charge the batteries of the tug.

FIG. 3A is a front view of the reel and cable assembly of FIG. 2 showingthe battery charging cable and associated connector in an extended andoperational state.

FIG. 3B is a frontal view of the reel and cable assembly of FIG. 2 withthe power cable and connector in a stowed and inoperative state.

FIG. 4A is a cross-sectional view of reel and cable assembly of FIG. 2taken along lines 4A-4A of FIG. 3A.

FIG. 4B is a cross-sectional view of the reel and cable assembly of FIG.2 taken along lines 4B-4B of FIG. 3B.

FIG. 5A is a cross-sectional view of the reel and cable assembly of FIG.2 taken long lines 5A-5A of FIG. 3A.

FIG. 5B is a cross-sectional view of the reel and cable assembly of FIG.2 taken along lines 5B-5B of FIG. 3B.

FIG. 6 is a simplified schematic diagram of control and indicatorcircuitry contained within the reel and cable assembly of FIG. 2.

FIG. 7 is a perspective view of a passenger boarding bridgeincorporating an alternate embodiment of the dual purpose solid statepower converter of the present disclosure wherein the battery chargingoutput cable is suspended from a hanger mounted on the housing of thepower converter when not in use.

FIG. 8 is a perspective view of the alternate embodiment of FIG. 7showing the battery charging cable connected to an adjacent electricallypowered aircraft tug.

FIG. 9 is a simplified schematic diagram of control and indicatorcircuitry incorporated in the dual purpose power converter shown inFIGS. 7 and 8.

FIG. 10 is a simplified functional block diagram of circuitry associatedwith the dual purpose power converter of FIGS. 1 and 2 for inhibitingmotion of the passenger boarding bridge when the power converter isbeing utilized to charge ground support equipment.

FIG. 11 a simplified functional block diagram of the dual purpose powerconverter of FIGS. 1 and 2.

FIG. 12 is a simplified partial schematic and functional block diagramof the dual purpose power converter of FIGS. 1 and 2.

FIG. 13 is an enlarged perspective view of a dual function powerconverter constructed in accordance with the disclosure mounted underthe cab of a passenger boarding bridge.

FIG. 14 is an enlarged perspective view of a dual function powerconverter constructed in accordance with the disclosure mounted on awheeled trailer for positioning by a tug.

FIG. 15 is a simplified schematic diagram of a dual function powerconverter constructed in accordance with the disclosure which providesDC ground power to a parked aircraft.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiments is merelyexemplary in nature and is in no way intended to limit the disclosure,its application or use.

Referring to the drawings, FIG. 1 illustrates a passenger boardingbridge 10 of conventional design and construction for boarding anaircraft 12. The passenger boarding bridge 10 provides an enclosed,movable passageway which extends from an airport terminal gate (notshown) to a door 16 of the aircraft, allowing passengers to board anddisembark the aircraft without being exposed to weather. The aircraftengaging end of the passenger boarding bridge is typically movable;moving up and down, swinging left and right, and extending toward andaway from the aircraft. Movement of the bridge is accomplished bymultiple electric motors which receive power through a power cable (notshown) extending along the bridge to the terminal.

FIG. 2 illustrates the passenger boarding bridge 10 of FIG. 1 in aretracted position and incorporating a dual function solid state powerconverter 18 of the present disclosure mounted under the cab 14 of thebridge. A reel and cable assembly 20 mounted on the wheeled carriage ofthe bridge enables the power converter to be connected to a parkedelectrically powered aircraft tug 22 by means of a cable 24 and a cableend connector 26.

The power converter 18 receives power from the terminal by means of acable (not shown) extending along the passenger boarding bridge. Thepower converter supplies ground power to aircraft 12 by means of a powercable 27, and battery charging power to tug 22 by means of a power cable24. To prevent the boarding bridge from moving while tug 22 is beingcharged, which could result in physical damage to tug 22 or power cable24, sensors within reel and cable assembly 20 detect when power cable 24is not stowed on the reel, and is therefore in use.

Referring first to FIG. 3A, a frontal perspective view of the housing 30of reel and cable assembly 20 is shown with cable 24 unwound from astorage reel 32. In this condition, with power switch 34 in the onposition, power available indicator 36 is illuminated and cable stowedindicator 38 is not illuminated. Furthermore, the power connector 26 inthis condition is not seated within the recess 40 provided on the frontpanel of housing 30 for stowing the connector. In contrast, the frontalperspective view of FIG. 3B shows the assembly 20 with power connector26 in a stowed position in recess 40, secured by a clamp 44, and powercable 24 wrapped around storage reel 32. In this condition, indicator 36is not illuminated, indicator 38 is illuminated, and movement of thepassenger boarding bridge is enabled.

The motion inhibiting function of reel and cable assembly 20 is furthershown in FIGS. 4A, 4B, 5A and 5B. Referring to FIG. 4A, when power cable24 is unwound from the reel 32, multiple spring-biased pressure switches46 a-46 d are unactuated and electrically open. Moreover, as shown inFIG. 5A, when connector 26 is not in recess 40, a spring-biased pressureswitch 48 is unactuated and electrically open. If any one of switches 46and 48 is in the open position, the power cable stowed indicator 38 isnot illuminated and movement of the passenger bridge is inhibited. Bycontrast, as shown in FIG. 4B, when power cable 24 is wound around reel32, the spring-biased pressure switches 46 a-46 d are actuated to anelectrically closed condition. Moreover, as shown in FIG. 5B, whenconnector 26 is seated in recess 40 and locked in place by latch 44,spring-biased pressure switch 48 is actuated to an electrically closedcondition. When all of the cable position sensing switches (46 a, 46 b,46 c, 46 d and 48) are in their electrically closed condition, cablestowed indicator 38 illuminates and movement of passenger bridge 10 isenabled.

Referring to FIG. 6, pressure actuated switches 46 a, 46 b, 46 c and 46d and 48 are electrically connected in series and through a cable 50 tothe cab 14 of passenger boarding bridge 10 to prevent the positioningmotors associated with the boarding bridge from being actuated when anyof the five switches is not in an electrically closed condition. Thecable stowed indicator 38 is powered from the boarding bridge controlcircuitry through cable 30 to indicate to ramp personnel that thepassageway is enabled for movement.

The power control switch 34 provided on the front panel 42 of housing 30is connected through a cable 52 to the control circuit of the dualfunction solid state power converter 18 such that the availability ofbattery charging power on power cable 24 can be controlled by ramppersonnel. The power available indicator 36 is also powered throughcable 52 by the power converter to indicate that battery charging poweris available. The battery charging power cable 24 is connected to powerconverter 18 through a separate cable 54.

An alternative embodiment of the disclosure, wherein the batterycharging cable 24 is suspended directly from power converter 18, isshown in FIGS. 7-9. Referring to FIG. 7, when in its stowed position,the battery charging power cable 24 is suspended from a hanger assembly56 on the side of the housing of power converter 18. When batterycharging cable 24 is in use and connected to the electrically poweredtug 22, the cable is removed from hanger 56 as shown in FIG. 8.

Referring to FIG. 9, hanger assembly 56 is mechanically coupled to aspring-biased pressure-actuated switch 58 such that when power cable 24is hanging from the hanger assembly in a stowed condition, switch 58 isactuated to an electrically closed condition. Conversely, when powercable 24 is removed from hanger 58 for use, switch 58 reverts to anelectrically open condition and movement of passenger bridge 10 isinhibited. A cable 60 provides connections between switch 58 and thepassenger bridge control circuits, as well as connections to the cablestowed indicator 38. A cable 62 provides connections between the batterycharging control switch 34 and power converter 18, as well asconnections between power available indicator 36 and power converter 18.Another cable 64 may be provided to supply battery charging power tocable 24 from power converter 18.

It will be appreciated that in practice the sensing, control andindicating circuitry shown in FIG. 9 may be incorporated directly intothe enclosure of power converter 18. Alternatively, a separate enclosure66 mounted on the outside surface of the power converter enclosure canbe provided as shown in FIG. 9.

As previously described, passenger boarding bridge 10 is positioned bymeans of electric motors such that it allows passengers to step from theend of the bridge into the door 16 of parked aircraft 12. Referring toFIG. 10, the bridge positioning system is seen to comprise a firstelectric motor 70 for steering the cab 14 of the bridge left and right.A second electric motor 72 is provided for extending and retracting thebridge toward and away from the parked aircraft. A third electric motor74 is provided to raise and lower the bridge to accommodate the heightof the aircraft door. Together, motors 70, 72 and 74 allow the passengerboarding bridge 10 to accommodate a wide range of aircraft parked at thegate associated with the bridge.

The three bridge positioning motors, 70, 72 and 74, are controlled bycontrol circuits 76 in response to operator inputs entered by means ofan operator control panel 78 in the cab 14 of the bridge 10. Inaddition, the bridge positioning system may include a position sensor 80which provides an additional input to control circuits 76 such thatsmall variations in the height of the aircraft are automaticallyaccommodated by the bridge elevation motor 74.

As previously described, and in accordance with one aspect of thedisclosure, the function of control circuits 76 is inhibited when thebattery charging function of the dual purpose solid state converter 18is in use. In particular, when power cable 24 is removed from reel 32 toconnect to tug 22 or other electrically powered ground serviceequipment, a switch is actuated as previously described to provide aninhibit signal to control circuits 76 which prevent the control circuitsfrom supplying power to any of motors 70, 72 and 74, regardless ofoperator inputs on control panel 78. When the battery charging functionis complete and the battery charging power cable 24 is restored to itsstorage condition on reel 32, or, in the case of the embodiment of FIGS.7-9, on hangar 56 to actuate switch 58, the inhibit signal is removedand control circuits 76 are again fully functional to allow positioningof passenger boarding bridge 10. Power available indicator 36 may bepowered by control circuits 76 to indicate when the charging function isactive and motion of the passenger boarding bridge is inhibited.

In practice, the bridge positioning motors and associated controlcircuits are powered by a three phase AC power source which may, or maynot, be the same power source that powers the dual purpose solid statepower converter 18.

Referring to FIG. 11, the dual purpose solid state power converter 18includes an input circuit 82 which receives three phase power from powerdistribution circuits in the airport terminal. This input circuit 82converts the three phase AC signal to a DC signal on a bus 84 which issupplied to an aircraft power circuit 86 and to a battery chargingcircuit 88. The aircraft power circuit 82 converts the DC power from bus84 to meet aircraft ground power requirements, in the presentembodiment, a three phase 115-200 volt 400 hertz current which issupplied as ground power to a parked aircraft. A monitoring circuit 90may be provided to monitor the current and voltage supplied to theaircraft and to cause a control circuit 92 to interrupt power to theaircraft should predetermined limits be exceeded.

The battery charger circuit 88 converts the DC power on bus 84 to alower voltage controlled DC current appropriate for charging batteriesin ground service equipment. Typically, this voltage will be in theorder of 28 volts DC and the current provided will be low, typically inthe order of 20 amps or less, depending on battery condition. Amonitoring circuit 94 monitors the output of battery charger circuit 88to interrupt operation of the charger circuit in the event predeterminedcurrent or voltage limits are exceeded. Additionally, voltage andtemperature monitoring circuits may be provided in association with thebatteries under charge in the ground service equipment to adjust thecharging voltage or the charging current as required.

Control circuit 92 includes connections to a battery charging rampcontrol panel to signal when the battery charger is in use and to allowramp personnel to control the charging function. Additional connectionsare provided for ramp personnel to control the application of groundpower to the aircraft.

Referring to FIG. 12, the dual function power converter 18 may include athyristor rectifier bridge circuit 100 and DC filter 102 of conventionaldesign and construction which converts a three-phase AC supply currentto a direct current on an internal bus 104. This direct current isapplied to a three-phase inverter 106 of conventional design andconstruction which converts the DC to a 400 hertz three-phase 115/200volt signal. This 400 hertz signal is filtered by a conventional filtercircuit 108 and applied to the primary windings of a three-phase outputtransformer 110. The secondary windings of output transformer 110 areconnected through a contactor 112 to cable 27 (not shown in FIG. 12)which connects the power supply to the electrical system of a parkedaircraft.

In accordance with the disclosure, the DC current developed on bus 104is simultaneously applied to a DC to DC converter 114 of conventionaldesign and construction. The lower voltage DC output of this converter,typically 28 volts DC, is connected through a contactor 116 to batterycharging current power cable 24 (not shown in FIG. 12) for chargingbatteries in electrically-powered aircraft tugs or otherelectrically-powered ground service equipment. The ramp vehicle beingthus charged may include a voltage sensor and a temperature sensor whichprovide signals to inputs 118 and 120, respectively, of the DC to DCconverter circuit. These sensing signals are utilized by the convertercircuit to maintain a charging current and voltage at the vehicleappropriate to the condition of the vehicle's battery.

The dual function power converter 18 preferably further includes acontrol circuit 122 which functions to control the operation ofthyristor rectifier 100, DC to AC inverter 106, and DC to DC converter114 in response to control signals applied to the converter at inputs124 and 126. Control circuit 122 further controls contactors 112 and116, and provides an external indication at 128 that aircraft supplycurrent is available and at 130 that battery charging current isavailable.

Referring to FIG. 13, dual function power converter 18 is preferablyenclosed within an enclosure 132 which provides protection against theweather while providing the internal circuitry of the converter withadequate ventilation and heat dissipation. In the case of the converterbeing utilized in conjunction with a passenger boarding bridge, theconverter may be advantageously mounted under the jetway with inputpower being provided to the converter by a cable extending the length ofthe bridge. The power output cables associated with the converter may besuspended from the bridge, or from the power converter enclosure, in themanner previously described. A control panel 134 may be provided on theexterior of the housing to provide for control and monitoring of theconverter by ramp personnel.

It will be appreciated that the power converter 18 can be alternativelymounted on a wheeled cart 136 and towed by a tug to an operatingposition, as shown in FIG. 14. Or, the power converter can be installedin a stationary position, such as within an airport terminal, andconnected to an aircraft and electrically powered ground supportequipment by a power cable of appropriate length.

It will be further appreciated that the dual function power converter ofthe disclosure can be provided as a converter 140 to supply parkedaircraft with DC power instead of AC ground power. In this case, asshown in FIG. 15, the three phase inverter 106 is replaced by a DC to DCconverter 142 which converts DC current available on DC bus 104 to alower voltage DC current, typically 28 volts DC. This lower voltage DCcurrent is supplied through contactor 112 to power cable 27 forapplication to a parked aircraft. In this case, output filter 108 andoutput transformer 110 are not required. The DC to DC converter 114provided for the battery charging function remains unchanged. In allother respects, dual function solid state converter 140 is identical topower converter 18, and may be utilized on a passenger boarding bridge,on a wheeled cart, or a stationary installation.

The foregoing detailed description has been given for clearness ofunderstanding only and no unnecessary limitations should be understoodtherefrom. Accordingly, while one or more particular embodiments of thedisclosure have been shown and described, it will be apparent to thoseskilled in the art that changes and modifications may be made thereinwithout departing from the invention if its broader aspects, and,therefore, the aim in the appended claims is to cover all such changesand modifications as fall within the true spirit and scope of thepresent disclosure.

What is claimed is:
 1. A dual purpose power converter, operable from an applied alternating current supply and providing a primary AC output current and a secondary DC output current, comprising: a rectifier circuit for converting the applied alternating current to a direct current; an inverter circuit for converting said direct current to the primary AC output current; and a direct current conversion circuit for converting said direct current to the secondary DC output current.
 2. A dual purpose power converter as defined in claim 1 wherein said rectifier circuit comprises a thyristor bridge circuit.
 3. A dual purpose power converter as defined in claim 2 wherein said thyristor bridge circuit includes a direct current filter.
 4. A dual purpose power converter as defined in claim 1 wherein said inverter circuit comprises a three phase DC to AC inverter circuit.
 5. A dual purpose power converter as defined in claim 4 wherein said DC to AC inverter circuit includes an output filter.
 6. A dual purpose power converter as defined in claim 5 wherein said DC to AC inverter circuit further includes an output transformer.
 7. A dual purpose power converter as defined in claim 1 wherein said DC to DC converter includes a regulation circuit responsive to output load voltage and load temperature.
 8. A dual purpose power converter operable from an applied alternating current supply and providing a primary AC output current and a secondary DC output current for use in a jetway adapted to service an aircraft parked on an associated ramp, comprising: a first cable set for connecting the primary AC output current to the aircraft; a second cable set for connecting the secondary DC output current to a ground service vehicle parked on the ramp; said second cable set having a deployed state enabling said cable to extend to the ramp to connect to said ground service vehicle, and a retracted state depending from the jetway and free and clear of the ramp; said jetway including an electrically-powered positioning system for positioning the jetway on the ramp relative to the aircraft; and a motion inhibit circuit including a switch actuated by said second cable set when said cable set is in said retracted state, for preventing movement of said jetway by said positioning system when said second cable set is not in said retracted state.
 9. A multi-purpose power converter as defined in claim 8 wherein said motion inhibit circuit comprises a switch disposed on said jetway and mechanically actuated by the position of said secondary cable set.
 10. A multi-purpose power converter as defined in claim 9 wherein said switch is actuated by the weight of said secondary cable set. 